Fan-Fold Foam Board Floral Park NY

Fan-fold foam board in Floral Park is widely marketed as an easy fix for improving the thermal performance and water resistance of walls when re-siding. But if not applied properly, this option could lead to moisture problems, according to leading building-science experts.

Best practice calls for stripping off existing siding, then installing a good weather barrier.

Fan-fold foam board is widely marketed as an easy fix for improving the thermal performance and water resistance of walls when re-siding. But if not applied properly, this option could lead to moisture problems, according to leading building-science experts.

At about ¼-inch-thick, fan-fold foam board adds only R-1 to R-1.5 to the wall system, a negligible insulation improvement. Foil-faced products promise higher R-values, but only when installed with a minimum ¾-inch air space in front of them, an option that requires siding over strapping. According to foam board manufacturers, the advantage of fan-fold is really that the board provides a consistent surface over the old siding, eliminating cracks and crevices that lead to energy-robbing drafts. All manufacturers recommend taping the foam to help stop air leaks and prevent water that gets through the siding from leaking behind the foam.

Photo: Courtesy THE JOURNAL OF LIGHT CONSTRUCTION

Certainly, the foam board provides a smooth working surface for installing new siding, but whether there is a significant improvement in thermal performance is hotly debated. “The danger is that you are putting an impermeable layer over the wall,” explains Steve Easley, a building consultant who specializes in helping building.

As interest in the environment grows, it's hard to turn on the television without seeing a story that offers advice on how consumers can go green. But while it's true that every little bit helps, there are no quick fixes on the road to sustainability. This is especially true in home building.